Technical Field
The present invention relates to a field-effect transistor, a display unit, a display, and a system using the field-effect transistor, and a method of manufacturing the field-effect transistor.
Description of the Related Art
Field-effect transistors (FETs) which can be switched on and off by application of a gate voltage are applied to displays employing active matrix as thin film transistors (TFTs), etc.
Transistors of bottom gate type using an oxide semiconductor for a semiconductor layer forming a channel area of a TFT have been developed. In general, oxide semiconductors are easily dissolved in etching liquid. This makes it difficult to conduct wet-etching in which an acid is used to conduct patterning a source electrode and a drain electrode on an oxide semiconductor. For this reason, lift-off methods are used in general. However, the lift-off methods generally have trouble with fine patterning and improving production yield.
In an attempt to solve this issue, a method has been proposed which includes providing an etching stopper layer of silicon oxynitride (SiOx) or silicon oxynitride (SiOxNy) on an oxide semiconductor to conduct etching a source electrode and a drain electrode.
As a protection layer to protect a thin-film transistor using an oxide semiconductor, a structure using a complex metal oxide including silicon (Si) and alkaline earth metal has been proposed.
As described above, if an etching stopper of silicon oxide (SiOx) or silicon oxynitride (SiOxNy) is formed on an oxide semiconductor layer, silicon oxide and silicon oxynitride are prone to cracking, peeling-off, etc. during heating in the post-process. This causes deterioration of property and uniformity of TFTs.